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United States Patent |
6,103,776
|
Rowland
,   et al.
|
August 15, 2000
|
Phenolic amides and their use as stabilizers
Abstract
Phenolic amides, useful as stabilizers for organic materials such as
polyols and polyurethanes, possess the general formula
##STR1##
wherein n is 0 to 3, R.sub.1 is alkyl of from 1 to about 6 carbon atoms,
R.sub.2 is hydrogen or alkyl of from 1 to about 6 carbon atoms, R.sub.3 is
hydrogen or hydrocarbyl of up to about 20 carbon atoms, optionally
containing one or more heterocyclic groups, R.sub.4 is hydrocarbyl of up
to about 20 carbon atoms, optionally containing one or more heterocyclic
groups, or R.sub.3 and R.sub.4 together with the nitrogen atom to which
they are bonded are joined together to form a heterocyclic group,
optionally containing one or more additional heterocyclic atoms.
Inventors:
|
Rowland; Robert G. (Woodbridge, CT);
Baranski; John R. (Southington, CT)
|
Assignee:
|
Uniroyal Chemical Company, Inc. (Middlebury, CT)
|
Appl. No.:
|
237062 |
Filed:
|
January 26, 1999 |
Current U.S. Class: |
521/164; 252/182.29; 521/166; 524/82; 524/86; 524/107; 524/222; 524/721; 528/73 |
Intern'l Class: |
C08G 018/30 |
Field of Search: |
524/222,82,86,107,721
528/73
521/164,166
252/182.29
|
References Cited
U.S. Patent Documents
4228297 | Oct., 1980 | Haeberli et al | 560/75.
|
Primary Examiner: Gorr; Rachel
Attorney, Agent or Firm: Thompson; Raymond D., Dilworth; Peter G.
Parent Case Text
This is a divisional application of Ser. No. 08/839,694 filed Apr. 15,
1997, is now U.S. Pat. No. 5,917,044.
Claims
What is claimed is:
1. A stabilized composition comprising an organic material which is
susceptible to degradation and in need of stabilization to prevent or
inhibit such degradation and a stabilization effective amount of at least
one phenolic amide stabilizer compound of the general formula
##STR8##
wherein n is 0 to 3, R.sub.1 is alkyl of from 1 to about 6 carbon atoms,
it being provided that at least one of R.sub.1 and R.sub.2 is t-butyl
R.sub.3 is hydrogen and R.sub.4 is alkyl of up to about 20 carbon atoms
containing a heterocyclic group.
2. The stabilized composition of claim 1 wherein the organic material which
is susceptible to degradation is a polyether polyol.
3. The stabilized composition of claim 1 wherein R.sub.4 is alkyl
containing a heterocyclic group derived from a heterocyclic compound
selected from 2-(2-aminoethyl)-1-methylpyrrolidine,
4-(2-aminoethyl)morpholine, 1-(2-aminoethyl) pyrrolidine,
1-(2-aminoethyl)piperidine, and 1-(2-aminoethyl)piperazine.
4. The stabilized composition of claim 1 wherein R.sub.1 and R.sub.2 are
t-butyl and R.sub.4 is alkyl containing a heterocyclic group derived from
a heterocyclic compound selected from
2-(-2-aminoethyl)-l-methyl-pyrrolidine, 4-(2-aminoethyl)morpholine,
1-(2-aminoethyl)pyrrolidine, 1-(2-aminoethyl)piperidine, and
1-(2-aminoethyl)piperazine.
5. The stabilized composition of claim 1 wherein the phenolic amide
stabilizer is
N-[2-(1-piperazinyl)ethyl]-3-(3,5-di-t-butyl-4-hydroxyphenyl) propionamide
6. A method for stabilizing an organic material which is susceptible to
degradation and in need of stabilization to prevent or inhibit such
degradation which comprises adding thereto a stabilizing amount of at
least one phenolic amide stabilizer of the general formula
##STR9##
wherein n is 0 to 3, R.sub.1 is alkyl of from 1 to about 6 carbon atoms,
R.sub.2 is hydrogen or alkyl of from 1 to about 6 carbon atoms, it being
provided that at least one of R.sub.1 and R.sub.2 is t-butyl R.sub.3 is
hydrogen and R.sub.4 is alkyl of up to about 20 carbon atoms containing a
heterocyclic group.
7. The method of claim 6 wherein the organic material which is susceptible
to degradation is a polyether polyol.
8. The method of claim 6 wherein R.sub.4 is alkyl containing a heterocyclic
group derived from a heterocyclic compound selected from
2-(2-aminoethyl)-1-methylpyrrolidine, 4-(2-aminoethyl)morpholine,
1-(2-aminoethyl)pyrrolidine, 1-(2-aminoethyl)piperidine, and
1-(2-aminoethyl)piperazine.
9. The method of claim 6 wherein R.sub.1 and R.sub.2 are t-butyl and
R.sub.4 is alkyl containing a heterocyclic group derived from a
heterocyclic compound selected from 2-(2-aminoethyl)-1-methylpyrrolidine,
4-(2-aminoethyl)morpholine, 1-(2-aminoethyl)pyrrolidine,
1-(2-aminoethyl)piperidine, and 1-(2-aminoethyl)piperazine.
10. The method of claim 6 wherein the phenolic amide stabilizer is
N-[2-(1-piperazinyl)ethyl]-3-(3,5-di-t-butyl-4-hydroxyphenyl)
propionamide.
11. A polyurethane foam obtained from a polyurethane foam-forming reaction
mixture containing as stabilizer for the foam a phenolic amide of the
general formula
##STR10##
wherein n is 0 to 3, R.sub.1 is alkyl of from 1 to about 6 carbon atoms,
R.sub.2 is hydrogen or alkyl of from 1 to about 6 carbon atoms, it being
provided that at least one of R.sub.1 and R.sub.2 is t-butyl R.sub.3 is
hydrogen and R.sub.4 is alkyl of up to about 20 carbon atoms containing a
heterocyclic group.
12. The polyurethane foam of claim 11 wherein R.sub.4 is alkyl containing a
heterocyclic group derived from a heterocyclic compound selected from
2-(2-aminoethyl)- 1 -methylpyrrolidine, 4-(2-aminoethyl)morpholine,
1-(2-aminoethyl)pyrrolidine, 1-(2-aminoethyl)piperidine, and
1-(2-aminoethyl)piperazine.
13. The polyurethane foam of claim 11 wherein R.sub.1 and R.sub.2 are
t-butyl and R.sub.4 is alkyl containing a heterocyclic group derived from
a heterocyclic compound selected from 2-(2-aminoethyl)-
1-methyl-pyrrolidine, 4-(2-aminoethyl)morpholine,
1-(2-aminoethyl)pyrrolidine, 1-(2-aminoethyl)piperidine, and
1-(2-aminoethyl)piperazine.
14. The polyurethane foam of claim 11 wherein the phenolic amide stabilizer
is N-[2-(1-piperazinyl)ethyl]-3-(3,5-di-t-butyl-4-hydroxyphenyl)
propionamide.
Description
BACKGROUND OF THE INVENTION
This invention relates to phenolic amides and the use of the amides as
stabilizers for polymers such as polyols and/or polyurethane foams.
The stabilization of polyalkylene polyether polyols and other polymeric
materials with antioxidants or other stabilizers and the use of the
stabilized polyols in the preparation of polyurethane foams to inhibit
scorch are well known to those skilled in the art. Polyether polyols used
in the manufacture of slabstock flexible urethane foam are typically
stabilized with antioxidant packages consisting of phenolic and amine
antioxidants and may also contain the synergist phenothiazine or a
phosphate moiety.
Illustrating such stabilization are U.S. Pat. Nos. 3,567,664 and 3,637,865
which disclose polyurethane foams stabilized with a mixture of
2,6-di-tert-butyl-4-methyl phenol [butylated hydroxy toluene (BHT)] and
p,p'-dialkyldiphenylamines.
BHT (2,6-di-t-butyl-4-methyl phenol) is the most common and widely used
hindered phenolic stabilizer for polyolefins, styrenics, vinyls, and
elastomers. However, there are problems associated with the use of BHT
such as long term discoloration, high volatility, sublimation, and
difficulty of use due to its solid form. Hindered 2,6-di-t-butyl phenolics
with various larger aliphatic groups replacing the methyl group in the
para-position of the BHT ring have succeeded in reducing volatility, but
usually at the expense of a reduction of activity of the antioxidant, as
the more substituted compounds contain relatively less of the hindered
hydroxy groups which provide the stabilization activity of hindered
phenolic stabilizers.
SUMMARY OF THE INVENTION
In accordance with the present invention, phenolic amides are provided
which possess the general formula
##STR2##
wherein n is 0 to 3, R.sub.1 is alkyl of from 1 to about 6 carbon atoms,
R.sub.2 is hydrogen or alkyl of from 1 to about 6 carbon atoms, R.sub.3 is
hydrogen or hydrocarbyl of up to about 20 carbon atoms, optionally
containing one or more heterocyclic groups, R.sub.4 is hydrocarbyl of up
to about 20 carbon atoms, optionally containing one or more heterocyclic
groups, or R.sub.3 and R.sub.4 together with the nitrogen atom to which
they are bonded are joined together to form a heterocyclic group,
optionally containing one or more additional heterocyclic atoms.
The foregoing phenolic amides are useful as stabilizers of organic
materials, e.g., polyether polyols to be used in the manufacture of
flexible and semiflexible polyurethane foam, which are subject to thermal
and oxidative deterioration or degradation caused by heat or light. When
added to the polyols and/or directly to the polyurethane foam-forming
reaction mixture containing such polyols, the phenolic amide stabilizers
inhibit scorch in the polyurethane foam product.
Many of the phenolic amide stabilizers of this invention are less volatile
than BHT and as such are less likely to escape into the environment than
the latter. Compared to the known esters, the amides of this invention are
more resistant to hydrolytic degradation, an advantageous property in
those applications where water/moisture may be present. The phenolic
amides of this invention possessing one or more amine groups exhibit
greater solubility compared with the prior art esters possessing long
alkyl chains and are therefore especially advantageous for use in
stabilizing polar materials.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The phenolic amides of this invention are obtained by reacting a phenolic
acid or derivative thereof of the general formula
##STR3##
wherein n, R.sub.1 and R.sub.2 have the aforestated meanings and Y is
alkoxy of from 1 to about 20 carbon atoms, hydroxy or halogen, with a
primary or secondary alkyl amine of the general formula
##STR4##
wherein R.sub.3 and R.sub.4 have the aforestated meanings.
Many of the starting phenolic acid compounds and their derivatives are well
known. See, e.g., U.S. Pat. Nos. 3,247,240, 3,330,859, 3,364,250,
3,642,868, 3,644,482, 3,801,540, 3,840,585, 4,085,132, 4,228,297,
4,529,809, 4,659,863, 5,089,656, 5,130,465, 5,264,612, and Re. 27,004, the
contents of which are incorporated by reference herein. A preferred
starting phenolic acid derivative for reaction with a primary or secondary
alkyl amine of this invention is methyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)
propionate.
Suitable amines for reaction with the foregoing phenolic acids and/or
derivatives thereof to provide the phenolic amides of this invention are
primary or secondary alkyl amines of aliphatic, cycloaliphatic or aromatic
structure optionally containing one or more heteroatoms such as nitrogen,
oxygen and/or sulfur. Specific amines include those in which R.sub.3 and
R.sub.4 are independently selected to be methyl, ethyl, propyl, isopropyl,
butyl, isobutyl, pentyl, hexyl, cyclohexyl, heptyl, octyl, 2-ethylhexyl,
nonyl, decyl, dodecyl, stearyl, oleyl, phenyl, benzyl, and the like,
containing e.g., up to about 20 carbon atoms, preferably no more than
about 18 carbon atoms and more preferably no more than about 12 carbon
atoms. Useful amines in which R.sub.3 and R.sub.4 together with the
nitrogen atom to which they are bonded are joined together to form a
heterocyclic compound include cyclic amines such as pyrrolidine,
piperidine, piperazine, morpholine, and the like. Also useful are amines
in which R.sub.3 and/or R4 are alkyl groups substituted with one or more
heterocyclic substituents. Examples of such amines are
2-(2-aminoethyl)-1-methylpyrrolidine, 4-(2-aminoethyl)-morpholine,
1-(2-aminoethyl)pyrrolidine, 1-(2-aminoethyl)-piperidine,
1-(2-aminoethyl)piperazine, and the like. Still other useful amines are
(aminoalkyl)alkylamines such as N-alkylethylene diamines,
N-alkyl-1,3-propane diamines, and the like.
The phenolic amides of this invention are obtained by reacting the phenolic
acid or derivative thereof and the primary or secondary alkyl amine in the
presence of a suitable catalyst, e.g., p-toluene sulfonic acid. The
reaction is advantageously conducted in a subsurface gas purge such as
nitrogen. A preferred temperature for this reaction is from about
110.degree. C. to about 250.degree. C. and more preferably from about
130.degree. C. to about 180.degree. C.
The phenolic amides of this invention are useful as stabilizers for organic
materials that are susceptible to degradation, e.g., deterioration due to
oxidation, elevated temperature and/or exposure to light or other actinic
radiation. Examples of such organic materials are synthetic organic
polymers such as vinyl resins formed from the polymerization of vinyl
halides or from the copolymerization of vinyl halides with unsaturated
polymerizable compounds. Examples of these unsaturated polymerizable
compounds include vinyl esters, alpha, beta-unsaturated acids, esters,
aldehydes, or ketones, and unsaturated hydrocarbons such as butadiene or
styrene.
Additional materials stabilized by the phenolic amide stabilizers of this
invention are poly-alpha-olefins such as polyethylene, polypropylene,
polybutylene, and polyisoprene, copolymers of poly-alpha-olefins,
polyamides, polyesters, polycarbonates, polyacetals, polystyrene, and
polyethylenoxide. Also included are copolymers such as high-impact
polystyrene containing copolymers of butadiene and styrene and those
formed by the copolymerization of acrylonitrile, butadiene, and styrene.
Other materials also stabilized include aliphatic ester lubricating oils,
animal and vegetable-derived oils, hydrocarbon materials such as gasoline,
diesel oil, mineral oil, fuel oil, drying oil, cutting fluids, waxes,
resins, and fatty acids such as soaps.
The phenolic amides of this invention are particularly useful for the
stabilization of polyether polyols and polyurethane foams derived
therefrom. Stabilization is required to protect these materials from
oxidative degradation, particularly at the high temperature encountered
during the reaction to make polyurethane foam. Polyether polyols are well
known in the art and are obtained by reacting polyhydric alcohols, e.g.,
those containing from 2-8 hydroxyl groups such as ethylene glycol,
propylene glycol, diethylene glycol, 2,3-butylene glycol, 1,3-butylene
glycol, 1,5-pentane diol, glycerol, trimethylolpropane, triethylolpropane,
sorbitol, pentaerythritol, and mixtures thereof, with a 1,2-epoxide, e.g.,
ethylene oxide, propylene oxide, butylene oxide, cyclohexane oxide,
glycidol and mixtures thereof. The preferred polyether polyols contain
from 2-4 hydroxyl groups and are obtained by reacting one or more
polyhydric alcohols having a like number of hydroxyl groups with ethylene
oxide, propylene oxide, butylene oxide, and mixtures thereof.
The phenolic amide stabilizer is added to the polyether polyol in an amount
sufficient to impart an appreciable stabilizing effect. In general, this
amount may vary from about 0.1 to about 2 weight percent, preferably from
about 0.2 to about 1 weight percent and more preferably from about 0.4 to
about 0.6 weight percent by total weight of polyether polyol.
Where the polyether polyol is to be employed in the manufacture of a
polyurethane foam, and stabilization of the polyol is not in issue, the
stabilizer composition can be added to some other component of the
polyurethane-forming reaction mixture, e.g., to the polyisocyanate, the
prepolymer, the foaming agent, etc., or to the reaction mixture once
formed, rather than to the polyol. In this case, the foregoing amounts of
phenolic amide stabilizer calculated on the basis of the total polyether
polyol component can be utilized,
Any suitable organic isocyanate which is capable of reacting with a polyol
to form a polyurethane can be employed in preparing the foam. This
includes diisocyanates and polyisocyanates, e.g., triisocyanates and
polymeric isocyanates. Due to their commercial availability, the polymeric
isocyanates and toluene diisocyanates are preferred. The latter, the use
of which is more preferred, can be supplied in the form of an isomeric
mixture of about 80 weight percent of the 2,4-isomer and about 20 weight
percent of the 2,6-isomer. Other typical isocyanates include
4,4'-methylene-bis(phenylisocyanate), 3,3'-bitolylene-4,4'-diisocyanate,
3,3'-dimethoxy-biphenylene-4,4'-diisocyanate,
naphthalene-1,5-diisocyanate, hexamethylene diisocyanate, 1,4-phenylene
diisocyanate, polyphenylene polymethylene isocyanate, etc. The amount of
isocyanate employed in the preparation of the polyurethane foams should be
sufficient to provide at least about 0.7 NCO groups per hydroxyl group
present in the reaction system. An excess of isocyanate compound can be
conveniently employed, however, the use of a large excess is generally
undesirable due to the high cost of the isocyanate compounds. It is
preferable, therefore, to employ no greater than about 1.5 NCO groups per
hydroxyl group, and still more preferably from about 0.9 to about 1.3 NCO
groups per hydroxyl group.
In preparing the polyurethane foams, the polyol containing the phenolic
amide stabilizer of this invention is reacted with the organic isocyanate
in the presence of a foaming agent and a reaction catalyst. The foaming
agent can be any of those known to be useful for this purpose, e.g.,
water. The amount of foaming agent employed can be varied within a wide
range. Generally, water is employed in an amount of from about 0.1 to
about 10 parts by weight of the polyol.
The catalyst used in preparing the polyurethane foams can be any of those
known to be useful for this purpose or mixtures thereof, including
tertiary amines and metallic salts. Typical tertiary amines include
N-methyl morpholine, N-hydroxyethyl morpholine, triethylene diamine,
dimethyl ethanolamine, tetramethylbutane diamine, trimethylamine,
triethylamine, etc. Typical metallic salts include the salts of antimony,
tin, and iron, e.g., dibutyltin dilaurate, stannous octanoate, etc.
Generally speaking, the catalyst is employed in an amount ranging from
about 0.1 to about 2.0 weight percent based on the weight of the polyol.
It is preferred in the preparation of the polyurethane foams of the present
invention to employ minor amounts of a surfactant in order to improve the
cell structure of the polyurethane foams. Typical of such surfactants are
the silicon-based surfactants as disclosed, e.g., in U.S. Pat. No.
2,834,748 and in the book "Rigid Plastic Foams" by T. H. Ferrigno (1963),
Reinhold Publishing Company. Other suitable compounds useful as
surfactants include synthetic detergents such as oxyethylated nonyl phenol
and other ethylene oxide and glycidol-based surfactants. Generally up to
about 2 parts by weight of the surfactant is employed per 100 parts by
weight of polyol.
Various additives can also be employed in preparing the foam which serve to
provide different properties. Fillers, e.g., clay, calcium sulfate, barium
sulfate, ammonium phosphate, etc., can be added to lower cost and improve
physical properties. Dyes can be added for color and fibrous glass or
synthetic fibers can be added for strength. In addition, plasticizer,
deodorants and flame retardants can be added.
The following examples are illustrative of the invention.
Microwave Oven Scorch Test
The Microwave Oven Scorch Induction Test (MOSIT) is a rapid, reproducible
bench scale test for the effectiveness of antioxidant packages which
correlates well with observed results from large scale industrial foams.
This procedure utilizes small hand-mixed foam buns to evaluate the
effectiveness of antioxidant packages. Because small buns will dissipate
the internal heat more rapidly than foam buns produced on an industrial
scale, a microwave oven is used to uniformly heat the foam bun by radiant
energy, rather than conducting heat through it by the use of a convection
oven. The microwave oven promotes heating of the small foam bun under
conditions which have the ability to create reproducible scorch within the
foam bun. Because humidity and temperature in the laboratory can affect
results, it is advisable for antioxidant package comparisons to be run
concurrently.
The formulation used to prepare foam bun samples is listed in Table I and
is typical of what is currently used by many major U.S. polyol
manufacturers in similar type testing.
TABLE 1
______________________________________
Flexible slabstock foam formulation.
______________________________________
Stabilized polyether polyol*
200.0 grams
Water (de-ionized) 10.0 grams
Amine catalyst (Dabco 33-LV, Air Products) 0.5 grams
Surfactant (Niax L-620, Air Products) 2.0 grams
Flame retardant (Fyrol FR-2, AKZO) 12.0 grams
Tin catalyst (Dabco T-10, Air Products) 0.4 grams
Toluene Diisocyanate (TDI-80/20, Olin) 124.5 grams
TDI index 109
______________________________________
*Polyether polyol A 3,000 average molecular weight polyol, when received
contains a minimum stabilization of approximately 100 ppm butylated
hydroxytoluene (BHT). This polyol is then further stabilized with AO
package to be evaluated.
The microwave oven employed in this testing was a 700 watt Whirlpool
TimeMaster. Prior to testing the first foam bun, the microwave oven is
pre-conditioned by placing a 1000 mL beaker containing 600 mL of water in
the microwave oven for 30 minutes at a power setting of 60%. A fresh
beaker is returned to the microwave oven for 15 minutes at a power setting
of 60% prior to each additional foam bun tested. This procedure is carried
out in order to maintain a constant temperature and humidity within the
microwave oven during testing.
The prepared foam formulation is poured into a 10".times.10".times.5"
cardboard box and allowed to rise. Five minutes after the appearance of
health bubbles across the surface of the foam bun, the sides of the
cardboard box are removed. The foam bun is immediately placed into the
preconditioned microwave oven. The foam is irradiated for a specified time
(usually about 15 minutes) at a power setting of 30%. The foam bun is
removed from the microwave oven, and immediately placed into an air
circulating oven for 3 minutes at 125.degree. C., to cure the hide of the
foam. Upon removal from the air circulating oven, the foam bun is
immediately cut in half, perpendicular to the rise of the foam, and
inspected for degree of scorch. A rating of "0" indicates no scorch while
a rating of "10" indicates very severe scorch. Two foams of each
formulation were prepared. The scorch ratings of each formulation were
averaged to give the results disclosed below.
EXAMPLE 1
This example illustrates the preparation and testing of the compound
##STR5##
Preparation:
To a 250 mL 3-neck round-bottom flask equipped with an overhead stirrer, a
sub-surface nitrogen purge and a condenser, a mixture of 53.46 g (0.183
mol) of methyl 3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate with 48.0 mL
(0.366 mol) of 1-(2-aminoethyl)-piperazine and 0.94 g (0.0049 mol)
p-toluene sulfonic acid monohydrate was added. The reaction mixture was
then stirred at 140.degree. C. for 15 hours with a moderate nitrogen purge
to produce a thick orange-yellow final product.
To the thick orange-yellow final product, 100 mL portion of reagent xylenes
was added. The product was washed two times with 100 mL of hot (90.degree.
C.) 0.1 M sodium bicarbonate solution and then washed twice with 100 mL
hot (90.degree. C.) de-ionized water. The solvent was removed using a
rotary evaporator. The final crude product was a light orange-yellow
glassy solid at 25.degree. C.
A 24 g portion of the final product was vacuum distilled. The distillate
was a light yellow, glassy solid at 25.degree. C. with a melting point of
50 to 55.degree. C. A 5 g sample of the distillate was recrystallized from
xylenes having a melting point of 109 to 111.degree. C.
Testing:
a) The following polyether polyol samples were prepared:
1. Standard containing 2500 ppm BHT and 2000 ppm Naugard-445.
2. Experimental sample containing 2500 ppm of Example 1.
______________________________________
Results:
Polyol Sample 1 2
______________________________________
Naugard-BHT ppm 2500 0
Naugard-445 ppm 2000 2000
Example 1 0 2500
Scorch Number* 2.0 2.0
______________________________________
*Scorch Number = 0-10, where 0 = no scorch and 10 = very severe scorch.
b) A repeat of Test (a) was conducted. The following polyether polyol
samples were prepared:
1. Standard containing 2500 ppm BHT and 2000 ppm Naugard-445.
2. Experimental sample containing 2500 ppm of Example 1.
______________________________________
Results:
Polyol Sample 1 2
______________________________________
Naugard-BHT ppm 2500 0
Naugard-445 ppm 2000 2000
Example 1 0 2500
Scorch Number* 1.0 1.0
______________________________________
*Scorch Number = 0-10, where 0 = no scorch and 10 = very severe scorch.
The result of this test was that equivalent performance was repeated.
c) Thermogravimetric Analysis of Example 1 versus BHT
This experiment was conducted to determine the volatility of the phenolic
amide stabilizer versus BHT.
Thermogravimetric Analysis (TGA) of neat antioxidants was a technique used
to measure volatility. Approximately 10 mg of sample is weighed into an
aluminum sample cup and then placed inside the chamber of a Perkin-Elmer
TGS-2 Thermogravimetric Analyzer. The chamber was equilibrated to
160.degree. C. under a nitrogen flow of 50 mL per minute, and run
isothermally for 250 minutes or until 100% weight loss of the sample is
experienced. A temperature of 160.degree. C. was used since it
approximates temperatures reached during production of large scale
industrial foams.
Results:
After 10 minutes at 160.degree. C. with a nitrogen flow of 50 mL/minute,
72% of the BHT had volatilized. After 250 minutes, only 1.6 percent of
Example 1 had volatilized.
EXAMPLE 2
This example illustrates the preparation and testing of the compound
##STR6##
Preparation:
To a 100 mL 3-neck, round-bottom flask equipped with an overhead stirrer, a
subsurface nitrogen purge and a condenser, 21.7 g (0.074 mol) of methyl
3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate with 21.5 g (0.137 mol) of
decyl amine and 0.47 g (0.0025 mol) p-toluene sulfonic acid monohydrate
was added. The mixture was stirred at 170.degree. C. for 15 hours with a
moderate nitrogen purge.
15 mL reagent xylenes was then added to dissolve the final product. The
product was washed two times with a 50 mL portion of hot (90.degree. C.)
0.1M sodium bicarbonate solution and then washed three times with 50 mL
portions of hot (90.degree. C.) de-ionized water. The solvent was removed
using a rotary evaporator and 27.7 g of a viscous yellow liquid was
recovered. The liquid was crystallized over a two week period with the
crystallized product having a melting point of 52 to 56.degree. C.
Testing:
The following polyether polyol samples were prepared:
1. Standard containing 2500 ppm BHT and 2000 ppm Naugard-445.
2. Experimental sample containing 2500 ppm Example 2 and 2000 ppm
Naugard-445.
______________________________________
Results:
Polyol Sample 1 2
______________________________________
Naugard-BHT ppm 2500 0
Naugard-445 ppm 2000 2000
Example 2 0 2500
Scorch Number* 3.0 3.0
______________________________________
*Scorch Number = 0-10, where 0 = no scorch and 10 = very severe scorch.
These results indicate equivalent performance of the experimental and the
standard containing BHT.
EXAMPLE 3
This example illustrates the preparation and testing of the compound
##STR7##
Preparation:
To a 100 mL 3-neck round-bottom flask equipped with an overhead stirrer, a
subsurface nitrogen purge and a 70.degree. C. knock-back condenser, a
mixture of 35.0 g (0.120 mol) of methyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)
propionate with 23.2 g (0.180 mol) of 2-ethylhexyl amine and 0.16 g
lithium amide was added. The reaction mixture was stirred at 160.degree.
C. for 15 hours with a moderate nitrogen purge.
The viscous light-yellow product was dissolved in 50 mL reagent xylenes and
washed with 200 mL 0.3M HCl. The product was then washed five times with
200 mL portions of de-ionized water. A rotary evaporator was used to
remove the solvent and 42.1 g of a light yellow viscous liquid was
recovered. The product was crystallized over a four week period with the
crystallized product having a melting point of 62 to 64.degree. C.
Testing:
a) The following polyether polyol samples were prepared:
1. Standard containing 2500 ppm BHT and 2000 ppm Naugard-445.
2. Experimental sample containing 2500 ppm Example 3 and 2000 ppm
Naugard-445.
______________________________________
Results:
Polyol Sample 1 2
______________________________________
Naugard-BHT ppm 2500 0
Naugard-445 ppm 2000 2000
Example 3 0 2500
Scorch Number* 2.0 1.5
______________________________________
*Scorch Number = 0-10, where 0 = no scorch and 10 = very severe scorch.
b) A repeat of Test (a) using PS-30 (a liquid amine commercially available
from Uniroyal Chemical Co.) as the amine stabilizer.
The following polyether polyol samples were prepared:
1. Standard containing 2500 ppm BHT and 2000 ppm Naugard-445.
2. Experimental containing 2500 ppm Example 3 and 2000 ppm Naugard PS-30.
______________________________________
Results:
Polyol Sample 1 2
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Naugard-BHT ppm 2500 0
Naugard-445 ppm 2000 0
Naugard PS-30 0 2000
Example 3 0 2500
Scorch Number* 3.00 2.75
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*Scorch Number = 0-10, where 0 = no scorch and 10 = very severe scorch.
There was a noticeable improvement in scorch protection using the
experimental stabilizer package versus the standard.
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